Blowing agent concentrate and compositions and article prepared therefrom

Abstract

The present invention includes an improved blowing agent concentrate, comprising: (a) a vinyl aromatic polymer; (b) a preformed blend of a styrene/diene block copolymer and a hydrocarbon rubber extending oil; and (c) at least one blowing agent. The blowing agent concentrate is utilized to prepare foamable materials based on a variety of thermoplastic organic polymers. The foamable materials can in turn be molded into a variety of thermoplastic structures.

I claim: 
     
       1. An improved blowing agent concentrate for thermoplastic polymers, comprising: (a) a vinyl aromatic polymer;   (b) a preformed blend of a styrene/diene block copolymer and a hydrocarbon rubber extending oil; and   (c) at least one blowing agent.   
     
     
       2. The concentrate of claim 1, wherein at least about 25% of the vinyl aromatic units in component (a) are derived from an alkenyl aromatic monomer of the formula ##STR4## wherein R 1  and R 2  are selected from the group consisting of hydrogen and lower alkyl or alkenyl groups of from 1 to 6 carbon atoms; R 3  and R 4  are selected from the group consisting of hydrogen and lower alkyl groups of from 1 to 6 carbon atoms; and R 5  and R 6  are selected from the group consisting of hydrogen and lower alkyl and alkenyl groups of from 1 to 6 carbon atoms; or R 5  and R 6  can be concatenated together with hydrocarbyl groups to form a naphthyl group. 
     
     
       3. The blowing agent concentrate of claim 2, wherein the vinyl aromatic polymer of component (a) is selected from the group consisting of homopolystyrene; poly-α-methylstyrene; a styrene maleic anhydride copolymer; and a styrene-acrylonitrile copolymer. 
     
     
       4. The concentrate of claim 1, wherein component (a) is rubber-modified. 
     
     
       5. The concentrate of claim 4, wherein component (a) is butadiene-modified homopolystyrene; and the weight ratio of butadiene to homopolystyrene is in the range of about 1:99 to about 20:80. 
     
     
       6. The concentrate of claim 1, wherein the styrene/diene block copolymer of component (b) is linear or branched. 
     
     
       7. The concentrate of claim 6, wherein the hydrocarbon rubber extending oil is selected from the group consisting of paraffinic oils, naphthenic oils, and mixtures thereof. 
     
     
       8. The concentrate of claim 6, wherein the styrene/diene ratio for component (b) is in the range of about 25:75 to about 55:45. 
     
     
       9. The concentrate of claim 6, wherein the level of extending oil ranges from about 5% by weight to about 55% by weight, based on the total weight of component (b). 
     
     
       10. The concentrate of claim 9, wherein the level of extending oil ranges from about 25% by weight to about 50% by weight. 
     
     
       11. The concentrate of claim 1, wherein the blowing agent of component (c) is selected from the group consisting of hydrazodicarboxylates, benzamides, amide derivatives of azodicarboxylic acid; hydrocerol, sodium borohydride, sodium bicarbonate-based compounds; aluminum hydroxide-based compounds; dihydrooxadiazinone-based compounds; and mixtures of any of the foregoing. 
     
     
       12. The concentrate of claim 11, wherein the amide derivatives of azodicarboxylic acid are compounds represented by the formula ##STR5## wherein R 3  and R 4  are independently selected from hydrogen and alkyl groups having from about 1 to about 10 carbon atoms. 
     
     
       13. The concentrate of claim 12, wherein the blowing agent is azodicarbonamide. 
     
     
       14. The concentrate of claim 1, wherein component (a) is present at a level of at least about 65%, based on the weight of the entire concentrate. 
     
     
       15. The concentrate of claim 1, wherein the blowing agent of component (c) is present at a level in the range of about 1% by weight to about 20% by weight, based on the weight of the entire concentrate. 
     
     
       16. The concentrate of claim 1, further comprising a poly(tetrafluoroethylene) resin. 
     
     
       17. The concentrate of claim 16, wherein the poly(tetrafluoroethylene) resin is present at a level in the range of about 0.01% by weight to about 2.0% by weight, based on the weight of the entire concentrate. 
     
     
       18. A foamable composition which comprises a thermoplastic organic polymer as a base resin, and a blowing agent concentrate which itself comprises: (a) a vinyl aromatic polymer;   (b) a preformed blend of a styrene/diene block copolymer and a hydrocarbon rubber extending oil; and   (c) at least one blowing agent compound.   
     
     
       19. The foamable composition of claim 18, wherein component (c) is an amide derivative of azodicarboxylic acid. 
     
     
       20. The foamable composition of claim 18, wherein the thermoplastic organic polymer is selected from the group consisting of polyimides, polyphenylene sulfide, styrene-acrylonitrile copolymers, acrylic-styrene-acrylonitrile terpolymers; acrylonitrile-butadiene-styrene (ABS) terpolymers, polycarbonates; alloys of polycarbonate and ABS; polyphenylene ether-based resins; polyamide resins; polystyrene-based resins; polyesters; elastomeric polyesters; polyolefins; blends of any of the foregoing; and copolymers of any of the foregoing. 
     
     
       21. A foamed, thermoplastic structure molded from a composition which comprises: (I) a thermoplastic organic polymer as a base resin, and   (II) a blowing agent concentrate which itself comprises: (a) a vinyl aromatic polymer;   (b) a preformed blend of a styrene/diene block copolymer and a hydrocarbon rubber extending oil; and   (c) at least one blowing agent compound.     
     
     
       22. The foamed structure of claim 21, prepared by injection molding.